The present invention broadly relates to a new and improved construction of a device for performing a start spinning operation, namely, starting or recommencing spinning of a yarn or the like in a friction spinning apparatus.
In its more particular aspects, the device for starting or recommencing spinning of a yarn in a friction spinning apparatus comprises friction spinning means containing a friction spinning surface provided thereon to which fibers are delivered. The fibers are formed into a twisted fiber structure or lap at a yarn formation position of the friction spinning means during the starting or recommencing of the spinning operation. The twisted fiber structure is withdrawn by a yarn withdrawal means, typically, a yarn withdrawal roller pair.
Previously known devices for the above-mentioned start spinning of a yarn, employ a yarn end withdrawn from a package. This yarn end is inserted into the stationary friction spinning means for start spinning and thereafter the start spinning operation is carried out at reduced speed of the friction spinning apparatus by feeding fibers to the yarn end withdrawn from the package. It has also been proposed that prior to start spinning, that is, before feed of freely floating fibers to the returned yarn end, the latter should be untwisted by movement of the friction spinning means in an opposite direction to enable better connection or interlacing of the delivered fibers with the yarn end.
Such a device is known from German Published Patent Application No. 3,318,687, in which a yarn end from a reverse rotated package is taken-up by a suction device and the yarn drawn-in by suction is held by means of two reciprocating devices in the convergent zone of two stationary friction spinning drums.
Before delivery of freely floating fibers to this yarn, the yarn is opened by reverse rotation of the friction spinning drums so that the fibers lie in a substantially twist-free condition in the convergent zone of the friction spinning drums. Thereafter, the friction spinning drums are placed into operation with reduced rotational speed in the normal direction of rotation and freely floating fibers are delivered to the opened yarn. The yarn which is thus produced, is withdrawn at a correspondingly reduced speed and delivered to a joining or connection means.
In order to take-up the continuously delivered yarn operation, the delivered yarn is received by a suction nozzle functioning as a yarn store or storage.
After completion of the joining or connection operation, the complete device is accelerated to the operating speed and thereafter is disconnected from the necessary auxiliary drive means and is driven by the normal drive means at the operating speed.
Certain of the disadvantages of a device of this type reside in the large amount of auxiliary equipment needed for the start spinning operation.
In the aforementioned U.S. Pat. No. 4,680,924, there is disclosed a method of start spinning of a yarn in a friction spinning device. Freely floating fibers are forwarded to a yarn formation position where such freely floating fibers are formed into a twisted fiber structure of a certain size. An airstream is used to forward the twisted fiber structure towards yarn withdrawal rolls. A shortcoming of such arrangement is that it is difficult to dose the airstream such that the twisted fiber structure is not entrained by the air which flows off in axial direction of the yarn withdrawal rolls. Should that happen, then there can arise the undesired situation that the twisted fiber structure is not engaged by the yarn withdrawal rolls.